As discussed in the parent disclosures which are incorporated herein by reference, many modern surgical procedures utilize small incisions through which instruments are inserted to perform the surgery in a minimally invasive manner.
One surgical technique delivers a suture loop to a tissue target, such as a polyp or the like. The loop is then placed around the target and the target is garrotted. The loop must be held open long enough and with sufficient size and stability to encircle the target and then must be managed to be efficiently tightened around the target. This is difficult to carry out in the environment associated with minimally invasive surgery. In some cases, it requires more than one person to effect the target garrotting, and even then can be onerous since the loop must remain open and in a stable configuration suitable for carrying out the procedure.
The parent disclosures discuss several prior art devices and techniques for effecting a ligating surgical technique. However, these prior techniques are difficult to carry out due to the problems mentioned above. The devices disclosed in the parent disclosures overcome these problems.
However, there is still room to improve the means and method disclosed in the parent disclosures. For example, the instruments used in the minimally invasive surgery are usually quite small; in fact, a five millimeter size is common. As the instruments get smaller, new problems are presented. Some tissue targets may actually be larger than the instrument. It may be difficult to capture large targets, especially using the prior devices such as discussed in the parent disclosures.
Therefore, there is a need for a suture ligating instrument which can be used in minimally invasive surgery, yet can accommodate tissue targets which are large in comparison to the device.
Still further, it is important for the ligature loop to be stable during insertion and setting. Ligature loop stability is achieved in the devices disclosed in the parent disclosures by locating the suture loop inside a hollow device. This works well when the target tissue is smaller than the device or can be efficiently drawn into the device.
If the device for ligating anatomical tissue can accommodate tissue targets larger than itself, its range of applications will be concomitantly increased. However, other considerations are required for targets that are larger than the device. For example, if the target is too large, it cannot be efficiently drawn into the device.
In some situations, it is desirable to have the instrument as small as possible. As the device, or instrument, gets smaller, the number of tissue targets larger than the device becomes larger, and the number of targets that may not be efficiently drawn into the device may also increase.
Therefore, there is a need for a suture ligating instrument which can be used in minimally invasive surgery and can efficiently accommodate large tissue targets, including targets that are larger than the device and targets that may not be drawn into the device in an efficient manner.
If the suture loop must accommodate a tissue target larger than the device, manipulation of the loop, including tightening the loop and cutting the suture material, must be carried out outside of the device. Since the prior devices do not accommodate such large tissue targets, they have no means for such outside loop manipulation.
Therefore, there is a need for a device for ligating anatomical tissue which can accommodate tissue targets larger than itself and which can effectively manipulate the surgical loop, even if that loop is located outside the main body of the device.
While holding the suture loop open in a stable manner is necessary, it is also necessary for an expeditious process that the loop also be handled in a stable manner so it will encircle and close about the target in a precise and accurate manner. At the present time, the inventors are not aware of any system that integrates a tissue manipulator with a suture loop holder. While the prior art does include loops on loop holders, these loop holders have several drawbacks, including allowing the loop to twist during manipulation, as well as the difficulty of maintaining the loop and the tissue properly oriented with respect to each other. Furthermore, a flaccid loop is often produced by these prior art devices.
In the environment of interest here, the thin, flexible and flaccid suture loop is extremely susceptible to collapsing prior to target acquisition. This presents a very difficult and frustrating problem to the surgeon. Furthermore, ligature loop stability becomes more difficult the larger the loop. Loop stability is not a problem in the devices disclosed in the parent disclosures since the loops are supported on the inside of the device. However, if the loop is to be used in connection with tissue larger than the device, the loop must be moved outside the device. Once the loop is moved outside the device, it cannot be supported in the manner disclosed in the parent disclosures. Loop support thus becomes a problem.
Therefore, there is a need for a system that can manage both tissue and the loop whereby the loop and the tissue remain properly oriented with respect to each other as required for an efficient ligating procedure, and which moves and controls the suture loop movement between an open configuration and a target encircling location in an accurate and precise manner. There is also a need for a device for ligating anatomical tissue which maintains a suture loop stable even for surgical targets that are large with respect to the device in which the loop must be located outside the body of the device for some portion of the procedure. Of course, this stability should be present during the entire procedure from initial insertion through and including garrotting the target.
Some targets will be smaller than others, and hence the device must be able to accommodate both large and small targets. Furthermore, since the target size may vary from extremely small to large and inflamed, the loop must be amenable to capturing a target that may have a size varying over a fairly large range. Therefore, there is a need for device for ligating anatomical tissue in which the loop and suture material is sized and adapted to accommodate both large and small tissue targets as well as targets in between the end size targets.
It is preferred that the loop be drawn down to the target size rather than enlarged to encircle the target. If the surgical loop is to be used with both small and large targets, if the loop is enlarged to encircle the large targets, its un-enlarged size may be too large for very small targets. This may degrade the results of the procedure, alternatively, it may reduce the size of the largest target that can be encircled by the loop since loops cannot be enlarged beyond a certain ratio. That is, the ratio between the smallest size of the loop and the largest size that the loop can be enlarged to will be limited by the elastic ratio of the material and the largest size loop cannot exceed a certain limit. Thus, the smallest size target will limit the range of target sizes.
Therefore, there is a need for a device in which the largest size of tissue target will not be depenent on the smallest size tissue target that can be captured by the surgical loop associated with the device.
In most surgical procedures, it is important to maintain what is known as margins. That is, a margin of extra tissue surrounding an operative site. In some cases, it means an extra margin of tissue around the excision of a lump or tumor. In the case of ligating anatomical structures, it means an extra margin of tissue left behind as a stump beyond the ligation site. This ensures that even if there is some physical stress induced at the site, the ligated ends of the tissue will not pull through the tightened suture loop and have a failure.
Therefore, the surgeon is concerned with establishing the proper tissue margins. However, in the prior art devices, when tissue is drawn into the bore of the prior art devices, it disappears from the surgeon's view. Thus, in the prior art, it is difficult to see how far one has retracted the tissue up into the bore with the tissue grasper. This in turn makes it difficult to determine the margin between the end of the tissue and the ligating loop.
Therefore, there is a need for a device that overcomes this shortcoming by providing a sight path to the tissue being ligated.
It is important to ensure that proper tension is applied by the suture loop to a tissue target. Too much tension on the loop may damage the tissue, and too little tension on the loop may vitiate the viability of the procedure. Setting proper tension may be easy when the tissue size is known. However, as discussed above, tissue size may vary over a fairly large range.
Therefore, there is a need for a device which automatically sets the proper tension of a suture loop regardless of the size of the tissue target.
Since most instruments used for minimally invasive surgery are expensive, it would be advantageous if some parts of the instruments could be re-used. Therefore, there is a need for device for ligating anatomical tissue which has some re-useable parts.
Since minimally invasive surgery has extreme space constraints, it is extremely difficult to carry out surgical steps that require more than one set of hands. Some ligature steps have, in the past, required one person to manipulate the loop while another person manipulates the tissue grasping elements. The means and method of the parent disclosures overcome this problem for tissue that is drawn into the instrument. However, there is a need to overcome this problem for larger tissue as well.
Therefore, there is a need for a device for ligating anatomical tissue which can accommodate large surgical tissue targets while still requiring only one person to carry out the procedure.